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| author |   Jiebin Sun <jiebin.sun@intel.com> | 2022-07-23 00:49:49 +0800 |
|---|---|---|
| committer |   akpm <akpm@linux-foundation.org> | 2022-07-29 18:07:17 -0700 |
| commit | 873f64b791a2b43c246e78b7d9fdd64ce909685b (patch) | |
| tree | 9b5a6645f92577e3393e2c347a942215b34fe2f4 /mm/memcontrol.c | |
| parent | userfaultfd: don't fail on unrecognized features (diff) | |
| download | linux-dev-873f64b791a2b43c246e78b7d9fdd64ce909685b.tar.xz linux-dev-873f64b791a2b43c246e78b7d9fdd64ce909685b.zip | |
mm/memcontrol.c: remove the redundant updating of stats_flush_threshold
Remove the redundant updating of stats_flush_threshold. If the global var
stats_flush_threshold has exceeded the trigger value for
__mem_cgroup_flush_stats, further increment is unnecessary.
Apply the patch and test the pts/hackbench-1.0.0 Count:4 (160 threads).
Score gain: 1.95x
Reduce CPU cycles in __mod_memcg_lruvec_state (44.88% -> 0.12%)
CPU: ICX 8380 x 2 sockets
Core number: 40 x 2 physical cores
Benchmark: pts/hackbench-1.0.0 Count:4 (160 threads)
Link: https://lkml.kernel.org/r/20220722164949.47760-1-jiebin.sun@intel.com
Signed-off-by: Jiebin Sun <jiebin.sun@intel.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Amadeusz Sawiski <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2b831cc48c7d..c65751ab4516 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -626,7 +626,14 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) x = __this_cpu_add_return(stats_updates, abs(val)); if (x > MEMCG_CHARGE_BATCH) { - atomic_add(x / MEMCG_CHARGE_BATCH, &stats_flush_threshold); + /* + * If stats_flush_threshold exceeds the threshold + * (>num_online_cpus()), cgroup stats update will be triggered + * in __mem_cgroup_flush_stats(). Increasing this var further + * is redundant and simply adds overhead in atomic update. + */ + if (atomic_read(&stats_flush_threshold) <= num_online_cpus()) + atomic_add(x / MEMCG_CHARGE_BATCH, &stats_flush_threshold); __this_cpu_write(stats_updates, 0); } } |